House.java

public abstract class House {
    protected Floor floor;
    protected Walls walls;
    protected Roof roof;
//getters and setters 

}

HouseBuilder.java

public abstract class HouseBuilder {
    protected House house;
    protected Floor floor;
    protected Walls walls;
    protected Roof roof;
    public abstract House createHouse();
    public abstract Floor createFloor();
    public abstract Walls createWalls();
    public abstract Roof createRoof();
}

HouseClient.java

public class HouseClient {
    public static void main(String[] args) {
        HouseDirector director = new HouseDirector();
        HouseBuilder woodBuilder = new WoodBuilder();
        BrickBuilder brickBuilder = new BrickBuilder();
// Build a wooden house
        House woodHouse = director.construcHouse(woodBuilder);
        System.out.println();
// Build a brick house
        House brickHouse = director.construcHouse(brickBuilder);
    }
}

HouseDirector.java

public class HouseDirector {
    public House construcHouse(HouseBuilder builder) {
        House house = builder.createHouse();
        System.out.println(house.getRepresentation());
        house.setFloor(builder.createFloor());
        System.out.println(house.getFloor().getRepresentation());
        house.setWalls(builder.createWalls());
        System.out.println(house.getWalls().getRepresentation());
        house.setRoof(builder.createRoof());
        System.out.println(house.getRoof().getRepresentation());
        return house;
    }
}

WoodBuilder.java

public class WoodBuilder extends HouseBuilder {
    public Floor createFloor() {
        floor = new WoodFloor();
        return floor;
    }
    public House createHouse() {
        house = new WoodHouse();
        return house;
    }
    public Roof createRoof() {
        roof = new WoodRoof();
        return roof;
    }
    public Walls createWalls() {
        walls = new WoodWalls();
        return walls;
    }
}